fix: Stock Ageing Report - Negative Opening Stock

[marination]

Issue:
Consider ledger:

1. -30, 1st Dec
2. 100, 2nd Dec
3. -10, 3rd Dec

• Stock Ageing Report ignored the first entry (no impact) as there is no existing qty in the FIFO Queue to consume from
• Hence, the total qty of the range columns here would show 30 qty more than the actual value [100 -10 (90) instead of -30+100-10 (60)]

Fix:

• Added a case to handle empty FIFO Queue. It could be empty because it was all consumed or because there was never any incoming stock
• Either way, add the negative qty to the queue
• When stock is added (+ve) add it to the negative balance to neutralise it until the balance is positive.
• Code cleanup: new class for FIFOSlots to generate chronological FIFO queue
  Usage

    FIFOSlots(filters).generate()

  

Dependencies/To Test:

• Stock Ageing Report end-to-end with various ledger scenarios (can pick up some from the .md file in this PR)
• Report warehouse wise item balance age and value
• Report stock balance with show ageing data checked

[codecov]

Codecov Report

Merging #28966 (09f26d8) into develop (21b0738) will increase coverage by 10.59%.
The diff coverage is 95.65%.

@@             Coverage Diff              @@
##           develop   #28966       +/-   ##
============================================
+ Coverage    44.95%   55.54%   +10.59%     
============================================
  Files         1128     1128               
  Lines        67295    67331       +36     
============================================
+ Hits         30251    37400     +7149     
+ Misses       37044    29931     -7113     

Impacted Files	Coverage Δ
...rpnext/stock/report/stock_balance/stock_balance.py	79.16% <50.00%> (+67.85%)	⬆️
erpnext/stock/report/stock_ageing/stock_ageing.py	93.06% <96.39%> (+81.38%)	⬆️
...value/warehouse_wise_item_balance_age_and_value.py	92.40% <100.00%> (+92.40%)	⬆️
...production_plan_summary/production_plan_summary.py	0.00% <0.00%> (-79.49%)	⬇️
...work_order_stock_report/work_order_stock_report.py	50.00% <0.00%> (-47.06%)	⬇️
erpnext/utilities/product.py	14.70% <0.00%> (-35.30%)	⬇️
erpnext/shopping_cart/product_info.py	30.30% <0.00%> (-21.22%)	⬇️
.../manufacturing/report/bom_explorer/bom_explorer.py	94.44% <0.00%> (-5.56%)	⬇️
...e/shopping_cart_settings/shopping_cart_settings.py	65.38% <0.00%> (-1.93%)	⬇️
erpnext/shopping_cart/product_query.py	61.19% <0.00%> (-1.50%)	⬇️
... and 258 more

[marination]

Sider failing on .md file, remark-lint was disabled for this repo, idk why its still failing

[marination]

@Mergifyio backport version-13-hotfix

[mergify]

backport version-13-hotfix

🟠 Waiting for conditions to match

• merged [:pushpin: backport requirement]

[mergify]

backport version-13-hotfix

✅ Backports have been created

• #29053 fix: Stock Ageing Report - Negative Opening Stock (backport #28966) has been created for branch version-13-hotfix